European Concerted Action on Anticoagulation (ECAA): an assessment of a method for ISI calibration of two whole blood point-of-care PT monitor systems based on lyophilized plasmas using whole blood equivalent PT.
ABSTRACT Previously, the attempt to simplify the International Sensitivity Index (ISI) calibration of the CoaguChek Mini whole blood point-of-care test prothrombin time (PT) monitor system was successful using lyophilized plasmas from coumarin-treated patients but not with lyophilized artificially depleted plasmas. With the TAS PT-NC monitor system, both types of plasma failed to provide reliable calibrations. The present study assesses a procedure for the ISI calibration of a TAS PT-NC and CoaguChek Mini whole blood point-of-care test PT monitor systems using lyophilized plasmas. Using lyophilized artificially depleted and coumarin plasma calibrations, we have evaluated a correction for the monitor displayed PT. This was based on a 'line of equivalence' derived from the relationship between whole blood and fresh plasma PT with both types of monitor system. With the TAS PT-NC, the use of this 'line of equivalence' resulted in reliable ISI with both lyophilized coumarin and artificially depleted plasmas. There was no significant difference between mean monitor and mean reference International Normalized Ratio (INR) with the artificially depleted plasmas. With the lyophilized coumarin plasma calibrations there was only a small INR difference. Correction with the 'line of equivalence' therefore facilitates calibration of the TAS PT-NC with lyophilized plasmas. With the CoaguChek Mini, the correction based on the 'line of equivalence' did not improve results but was not required with this system.
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ABSTRACT: The International Normalized Ratios (INRs) measured by two point-of-care (POC) devices were compared with those obtained via laboratory-based venipuncture. In an outpatient, pharmacist-managed anticoagulation clinic, 52 patients receiving oral warfarin therapy had their INR values measured using two POC devices, i-STAT PT/INR (Abbott Laboratories, Abbott Park, IL) and CoaguChek XS Plus (Roche Diagnostics, Indianapolis, IN). At the same visit, one venous blood sample was collected from each patient for INR measurement by the reference laboratory's instrumentation (STAGO, Diagnostica-Stago, Parsippany, NJ). Accuracy was evaluated by calculating the absolute difference for each set of INR values. Clinical correlation was defined as an INR measurement obtained by the POC devices that would have resulted in the same therapeutic decision as the INR value measured by the reference laboratory's instrumentation. Accuracy was superior with the CoaguChek XS Plus device. The absolute difference (mean ± S.D.) in the INR measurements obtained using STAGO versus CoaguChek XS Plus was 0.28 ± 0.31 (p < 0.0001). The absolute difference in INR values measured using STAGO and the i-STAT PT/INR device was 0.51 ± 0.44 (p < 0.0001). For clinical correlation, 17 (33%) of 52 INR measurements with the CoaguChek XS Plus were sufficiently different from the STAGO-measured INR values to have resulted in a different therapeutic decision (p < 0.001), compared with 28 (54%) of 52 with the i-STAT PT/INR (p < 0.001). INR measurements generated by POC devices exhibited positive bias, compared with laboratory-based venipuncture, for INR values at the high end of the INR range.American journal of health-system pharmacy: AJHP: official journal of the American Society of Health-System Pharmacists 10/2010; 67(19):1616-22. · 2.10 Impact Factor
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ABSTRACT: A system for quality assessment (QA) of the CoaguChek (Roche Diagnostics, Mannheim, Germany) point-of-care testing prothrombin time monitor has been developed by the European Concerted Action on Anticoagulation. Hitherto there has not been an adequate rapid method for CoaguChek QA. Sets of 5 certified international normalized ratio (INR) plasma samples were tested on 539 CoaguChek monitors by experienced staff at 9 Netherlands Thrombosis Centers and results compared with certified INR. A 15% or more deviation has been classified as significant deviation. Overall mean and certified INR values were similar, but 20.3% of participants showed a 15% or more deviation from the certified INR on at least 1 of the 5 QA plasma samples. Statistically significant differences in results with different lots of CoaguChek test strips were found. There is need for large scale QA of CoaguChek monitors. The importance of the 5 CoaguChek certified INR QA plasma samples being tested on a single occasion is demonstrated.American Journal of Clinical Pathology 12/2006; 126(5):756-61. · 2.88 Impact Factor
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ABSTRACT: The use of oral anticoagulant therapy is increasing in children. Managing anticoagulant therapy in children presents unique challenges, including poor venous access. The advent of point-of-care (POC) monitoring of anticoagulant therapy offers a potential solution to this challenge. This paper reviews the published literature relating to POC monitoring of oral anticoagulant therapy in children. A Medline search was conducted and identified key publications. Papers were reviewed with respect to their objectives, populations and POC device investigated. Study limitations were identified. Five publications and one abstract were identified, reporting studies using five different POC monitors. Three studies had a strong clinical management focus. Outcome measures assessed included target therapeutic range achievement and frequency of adverse events. Correlation between POC and laboratory-based results ranged from 0.83 to 0.96. Home monitoring and self-management using POC monitors were both reported to be preferred compared to standard laboratory testing. POC monitoring of oral anticoagulant therapy in children offers considerable advantages. The reviewed literature would suggest such monitoring can be performed accurately and reliably. The impact of quality control issues, such as calibration of thromboplastin ISI in POC devices, has not been explored in a paediatric population. Further studies are needed to clarify such issues and confirm the safety, reliability and efficacy of POC monitoring of oral anticoagulant therapy in children, including its home monitoring and self-management programs.Thrombosis Research 02/2006; 118(1):113-21. · 3.13 Impact Factor